1. Field of the Invention
The invention relates generally to electrodes and methods for making the same, more particularly, to an electrode having a high specific surface area thereof and a method for making the same.
2. Discussion of Related Art
In recent years, demand has been growing for more compact and thin electronic equipment, thus capacitors and batteries used in electronic equipment are also required to be thin whilst also providing high capacitance. For example, in a non-contact IC card, the thickness thereof is as thin as 1 mm or less, so the thickness of the capacitors included therein should be several hundred microns or less.
A parallel plate capacitor is one kind of conventional charge storage device. The basic design of these capacitors involves two conductive electrodes separated by a dielectric or insulative thin film material. To provide increased capacitance, one or both electrodes of the storage capacitors can be formed with a roughened surface, such as that which is provided by hemispherical grained (HSG) polysilicon, so as to increase the area over that which is provided by electrodes having planar surfaces. Other methods of providing increased capacitance involve using an insulating material having an increased dielectric constant and reducing the thickness of the dielectric insulating layer so as to reduce the distance between the electrodes.
While many variations of this type of capacitor have been developed, all of the known designs suffer from many disadvantages, having complicated structures, high construction costs and poor surface quality. Furthermore, mechanical strength becomes poorer as the capacitor becomes thinner.
What is needed, therefore, is an electrode having high capacitance and simple structure.